JP2005172639A - Sample thermostat device and automatic sampler using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermostat device for correcting temperature unevenness at the sample cooling time. <P>SOLUTION: The bottom surface 24 of a sample rack 2 is placed on a cooling part 14. The cooling part 14 has a Peltier element 16 as an electronic cooling element, and the first cooling plate 18 is provided adhesively on one surface of the Peltier element 16, and the second cooling plate 10 is additionally provided adhesively on the cooling plate 18. A heat insulating material 22 is buried into the center part on the surface of the cooling plate 10. Since the heat insulating material 22 is buried into the center part of the contact face between the cooling plate 10 provided on the Peltier element 16 through the cooling plate 18 and the bottom surface 24 of the sample rack as a heat insulating layer, supercooling at a part close to the Peltier element 16 is prevented. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a sample thermostat for keeping a sample cooled to a constant temperature and an autosampler using the same.

  In order to inject a sample into an injection port (injection unit) connected to an analysis column of a liquid chromatograph, a liquid chromatograph autosampler moves a sampling needle in a horizontal plane direction and a vertical direction to move a sample container (sample A certain amount of sample is inhaled from the vial) and then moved to the injection port to inject the sample. In the autosampler, a plurality of sample containers are stored in a sample rack provided inside the autosampler apparatus. Usually, the sample rack is cooled by a Peltier element through a plate of a highly heat conductive metal in order to keep the sample container cold.

FIG. 3 is a cross-sectional view showing a conventional sample thermostat and sample rack.
A cooling unit 14 is provided below the sample rack containing the sample container 3. The cooling unit 14 includes a cooling plate on one surface of the Peltier element 16, and radiating fins 20 on the other surface. The Peltier element 16 cools the cooling plate 18, and the cooling plate 18 cooled by the Peltier element 16 cools the cooling plate 24 on the bottom surface of the sample rack. The plurality of sample containers 3 housed in the sample rack are directly contacted with the bottom surface of the sample rack and cooled by the cooling plate 24.

In the method of cooling the sample container by bringing the cooling plate 18 of the cooling unit into direct contact with the sample rack, the area of the cooling plate 24 is larger than the area of the Peltier element 16 in order to cool a plurality of sample containers. Therefore, temperature unevenness occurs in the surface of the cooling plate 24, and temperature unevenness occurs between the sample containers. If temperature unevenness occurs between sample containers, it causes problems such as poor reproducibility of quantitative results during analysis.
Therefore, an object of the present invention is to correct temperature unevenness during sample cooling.

  The sample thermostat of the present invention cools the cooling plate by contacting a plurality of sample containers containing samples directly on the surface side surface to cool the sample container, and contacting the back surface of the cooling plate. And a cooling unit that includes an electronic cooling element having a cooling surface with a smaller area than the back surface of the cooling plate, and the cooling surface of the electronic cooling element is a central portion of the back surface of the cooling plate. It is arrange | positioned so that it may be located in the center part of the cooling surface of the said electronic cooling element between the cooling surface of the said electronic cooling element, and the back surface of the said cooling plate rather than the cooling surface of the said electronic cooling element A heat insulating layer having a small area is formed.

An example of the cooling plate that comes into contact with the sample container is a bottom plate of a sample rack that houses the sample container and is detachably in contact with the cooling unit.
As the electronic cooling element, for example, a Peltier element can be used.
The heat insulating layer may be an air layer or may be embedded with a heat insulating material such as foamed silicon.

The autosampler of the present invention holds a plurality of liquid samples at a constant temperature by a sample thermostat and supplies the samples to the analyzer, and the sample thermostat has the above-described configuration. It is a feature.
An example of the analyzer in that case is a liquid chromatograph.

  Between the cooling surface of the electronic cooling element and the back surface of the cooling plate, a heat insulation layer having an area smaller than the cooling surface of the electronic cooling element is formed at the center of the cooling surface of the electronic cooling element. It is possible to prevent the portion from being overcooled, and to correct the temperature difference between the central portion of the cooling plate and the surface away from the central portion.

  By applying this sample thermostat to the autosampler, a plurality of sample containers can be cooled and stored with a small temperature difference.

An embodiment of the autosampler according to the present invention will be described below.
FIG. 1 is a perspective view showing a configuration of an autosampler.
This autosampler includes a sample rack 2 for storing a sample container for putting a sample in the cold storage container 1, a cooling unit 14 provided for cooling the sample container stored in the sample rack 2, and a sample container And a sampling needle 4 for inhaling a sample. In FIG. 1, the front surface of the cold container 1 is shown as being open, but the opening is closed with a lid when in use. The sample rack 2 is detachably mounted on the cooling unit 14.

  The sampling needle 4 can move in the horizontal plane direction (X, Y direction) and the vertical direction (Z direction), and moves to the position of the sample container accommodated in the sample rack 2 to suck the sample from the tip of the needle. To do. The sample sucked by the sampling needle 4 is injected into the analysis flow path of the liquid chromatograph, sent to the separation column, and separated and analyzed for each component.

FIG. 2 is a cross-sectional view showing the periphery of the sample rack 2, (A) is a side view, and (B) is a top view of the cooling plate of the cooling unit 14.
As shown in (A), the bottom surface 24 of the sample rack 2 is placed on the cooling unit 14. The cooling unit 14 includes a Peltier element 16 as an electronic cooling element, and a first cooling plate 18 is provided in close contact with one surface of the Peltier element 16, and the second cooling plate 10 is further in close contact with the cooling plate 18. Is provided. A heat insulating material 22 is embedded in the center of the surface of the cooling plate 10. A heat radiating fin 20 is provided on the other surface of the Peltier element 16. The sample rack 2, the first cooling plate 18, the second cooling plate 10, and the heat radiating fins 20 are made of a highly heat conductive metal such as aluminum, copper, or brass. The heat insulating material 22 is, for example, foamed silicon.

  As shown in FIG. 5B, in this embodiment, the length L1 of the cooling plate 24 on the bottom surface of the sample rack that accommodates the plurality of sample containers 3 is longer than the length L2 of the cooling plates 18 and 10 of the cooling unit 14. The width W is equal in the cooling plate 24, the cooling plate 10 and the cooling plate 18. Further, the heat insulating material 22 is installed so that the width W is equal to that of the cooling plate 10, and the width A in the length direction is shorter than the length of the Peltier element 16 and is located at the center of the Peltier element 16.

  In the conventional cooling unit, the sample rack is cooled by the cooling plate 18 provided in close contact with the Peltier element. There was a temperature difference between the outside. In this embodiment, since the heat insulating material 22 is embedded as a heat insulating layer in the center of the contact surface between the cooling plate 10 provided on the Peltier device 16 via the cooling plate 18 and the bottom surface 24 of the sample rack, the Peltier device 16 The overcooling of the nearest part is prevented, and the temperature difference between the central portion of the sample rack bottom surface 24 and the outside thereof can be corrected.

In order to reduce the in-plane temperature distribution of the cooling plate, a plurality of Peltier elements can be used. However, according to the present invention, since the in-plane temperature distribution can be improved with one Peltier element, the cost can be suppressed.
The position where the heat insulating material 22 is embedded may be between the first cooling plate 18 and the second cooling plate 10 in addition to the surface of the second cooling plate 10.
As the heat insulating layer, an air layer may be formed in addition to embedding a heat insulating material.

It is a perspective view which shows the structure of the autosampler of one Example. It is sectional drawing which shows the sample rack vicinity. It is sectional drawing which shows the sample rack vicinity of the conventional apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cold storage container 2 Sample rack 3 Sample container 4 Sampling needle 10 2nd cooling plate 12 Separation column 14 Cooling part 16 Peltier element 18 1st cooling plate 20 Radiation fin 22 Heat insulating material 24 Cooling plate

Claims (6)

A cooling plate that cools the sample container by directly contacting a plurality of sample containers containing the sample on the surface side;
A cooling unit that contacts the back surface of the cooling plate and cools the cooling plate;
The cooling unit includes an electronic cooling element having a cooling surface with a smaller area than the back surface of the cooling plate, and the cooling surface of the electronic cooling element is positioned at the center of the back surface side of the cooling plate. Are located in
Between the cooling surface of the electronic cooling element and the back surface of the cooling plate, a heat insulating layer having an area smaller than the cooling surface of the electronic cooling element is formed at the central portion of the cooling surface of the electronic cooling element. A sample thermostat.   2. The sample thermostat according to claim 1, wherein the cooling plate is a bottom plate of a sample rack that houses the sample container and detachably contacts the cooling unit.   The sample thermostat according to claim 1 or 2, wherein the electronic cooling element is a Peltier element.   The sample thermostat according to any one of claims 1 to 3, wherein a heat insulating material is embedded as the heat insulating layer. In an autosampler that holds a plurality of liquid samples at a constant temperature by a sample thermostat and supplies these samples to an analyzer,
An autosampler comprising the sample thermostat according to any one of claims 1 to 4 as the sample thermostat. The autosampler according to claim 5, wherein the analyzer is a liquid chromatograph.

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